FIG. 5.

Neutralizing antibody titers (geometric mean) after the fourth and fifth immunizations. Experiments were performed by using the M7-luc assay. Titers are the reciprocal of the highest serum dilution at which relative RLU were reduced 50% compared to virus control wells (no test sample). Groups are described in Table 1. (A) Neutralizing antibody titers against the neutralization-sensitive HIV-1 subtype B SF162 primary isolate. (B) Neutralizing antibody titers against homologous HIV-1 subtype C TV1 primary isolate. Neutralizing antibodies against subtype C TV1 for the C-gp140ΔV2 (group 6) appeared higher compared to C-gp140 (group 5) at 2 weeks after the second protein boost (2wp4, P = 0.0548). After the third protein (2wp5), a significant difference was seen for C-gp140ΔV2 versus C-gp140 (P = 0.0491).